Long fiber-reinforced polymer alloy resin composition

ABSTRACT

A long fiber-reinforced polymer alloy resin composition (C) is provided which is obtained by blending a master batch (A) containing a long fiber reinforcement (a2) having a length of 3 to 30 mm in a resin matrix of a polyamide resin (a1), with a substantially polymer-alloyed resin diluent (B) obtained by melt kneading 45 to 20% by weight of a crystalline polyolefin resin (b1) and 55 to 80% by weight of a polyamide resin (b2), the crystalline polyolefin resin (b1) containing a modified olefin crystalline polymer (b11) having been substantially modified with unsaturated carboxylic acids. In this resin composition (C), the amount of the long fiber reinforcement (a2) is in the range of 10 to 60% by weight, and the amount of the crystalline polyolefin resin (b1) in resin components ((a1)+(b1)+(2)) other than the long finer reinforcement (a2) is in the range of 20 to 45% by weight. This resin composition (C) is excellent in tensile strength and particularly excellent in repeated impact resistance properties.

TECHNICAL FIELD

The present invention relates to a long fiber-reinforced polymer alloyresin composition which is suitable for injection molding and isexcellent in dispersibility of the long fiber reinforcement in themolded article produced therefrom and excellent in the reinforcingeffect exerted by the long fiber reinforcement, mechanical strength,especially tensile strength and flexural strength, and repeated impactresistance properties.

BACKGROUND ART

The "long fiber-reinforced polyamide resin composition" is obtained by,for example, impregnating a reinforcing long fiber bundle with a moltenpolyamide resin. Reinforced molded articles obtained from the longfiber-reinforced composition exhibit prominently improved impactresistance as compared with conventional short fiber-reinforced moldedarticles. The reason is presumably that the long fiber-reinforcedcomposition (pellet) contains reinforcing fibers having a lengthsubstantially equal to that of the pellet. Because of its excellentproperties, the long fiber-reinforced polyamide resin composition hasbeen widely used.

However, the polyamide resin is desired to be further improved inlightweight properties, hygroscopicity and cost performance (because ofits high cost), though it has high heat resistance. In addition thereto,the polyamide resin is unexpectedly brittle when repeatedly subjected toshock (that is, poor in repeated impact properties), though it is goodin ordinary impact resistance. Therefore, the use of the polyamide resincomposition is specifically limited.

In this connection, Japanese Patent Laid-Open Publication No. 58458/1985proposes a composition comprising a specific modified polypropylene aspecific polyamide and a fiber reinforcement. It is described in thispublication that a composition which has heat resistance almost equal tothat of polyamide and is highly improved in lightweight properties,hygroscopicity and cost performance can be obtained according to thisinvention. However, a means to prepare the composition disclosed in thepublication is only a method of melt kneading a resin and preliminarilychopped glass fibers by an extruder or the like. According to theadditional tests, molded articles obtained from the composition isentirely insufficient not only in repeated impact resistance propertiesbut also in impact resistance.

The present inventors have already invented a novel longfiber-reinforced resin composition, that comprises a resin matrix of a"polymer alloy" made from a polyamide resin and a modified olefincrystalline polymer prepared by graft modification with unsaturatedcarboxylic acids, particularly, a modified propylene crystallinepolymer, to which long fiber reinforcement is homogeneously added.According to this invention, there can be obtained a longfiber-reinforced resin composition which is excellent in lightweightproperties, cost performance and ordinary impact resistance and,moreover is remarkably improved in repeated impact resistance.

In fields where much higher performance is required for molded articlesproduced from long fiber-reinforced compositions, however, there is roomfor improvement in the dispersibility of the long fibers in the moldedarticles to thereby enhance mechanical properties such as tensilestrength. Further, the glass fiber reinforcement in the form of smallbundles remains in the molded articles because of lack of loosening ofbundles, and, thefore, the molded articles sometimes have badappearance. Furthermore, there remains room for further improvement inrepeated impact resistance of the molded articles.

As another prior art technique, a resin composition comprising athermoplastic resin containing fibers (first resin) and other resin(second resin) having a melting point lower than that of the first resinhas been proposed in Japanese Patent Publication No. 60780/1993. In thispublication, it is described that the second resin is melted prior tomelting of the first resin and includes the first resin. Therefore,folding of the fibers is inhibited by the first resin, and as a result,the molded article can be improved in mechanical strength, rigidity andheat resistance. According to the studies by the present inventors,however, the degree of the improvement in the mechanical strength of themolded article is still insufficient, though the folding of the fibersin the molded article is undoubtedly improved (reduced). Further, therepeated impact resistance is never improved, though the ordinary impactresistance is improved.

As is apparent from the above, a fiber-reinforced resin compositionshowing high dispersibility of fibers in the molded article andexcellent in all of the lightweight properties of the molded article,cost performance, mechanical strength and the repeated impact resistanceproperties has been eagerly desired, but no satisfactoryfiber-reinforced resin composition has been obtained yet. Accordingly,it is an object of the present invention to provide a fiber-reinforcedcomposition excellent in these properties.

DISCLOSURE OF THE INVENTION

Under such circumstances as mentioned above, the present inventors havefound that a novel long fiber-reinforced resin composition (C) obtainedby blending a master batch of long fiber-reinforced resin (A) containinga polyamide resin (a1) as a resin matrix with a specific polymer-alloyedresin diluent (B) to thereby make the components contained in a specificratio, is excellent in the mechanical strength such as tensile strengthof its molded article, and is excellent in repeated impact resistance.As a result of further studies by the present inventors, the presentinvention has been accomplished. The present invention resides in thefollowing items.

(1) A long fiber-reinforced polymer alloy resin composition (C) obtainedby blending:

a master batch (A) containing a long fiber reinforcement (a2) having alength of 3 to 30 mm in a resin matrix of a polyamide resin (a1); and

a substantially polymer-alloyed resin diluent (B) obtained by meltkneading 20 to 45% by weight of a crystalline polyolefin resin (b1),said crystalline polyolefin resin (b1) comprising a modified olefincrystalline polymer (b11) having been modified with unsaturatedcarboxylic acids (b12), and 55 to 80% by weight of a polyamide resin(b2);

in which the amount of the long fiber reinforcement (a2) is in the rangeof 10 to 60% by weight, and the amount of the crystalline polyolefinresin (b1) in resin components ((a1)+(b1)+(b2)) than the long fiberreinforcement (a2) is in the range of 20 to 45% by weight.

2) The long fiber-reinforced polymer alloy resin composition (C)according to above item (1), wherein the resin diluent (B) is composedof 60 to 75% by weight of the polyamide resin (b2) and 20 to 40% byweight of the crystalline polyolefin resin (b1), the total amounts ofsaid components (b1) and (b2) being 100% by weight.

3) The long fiber-reinforced polymer alloy resin composition (C)according to the above item (1) and the above item (2), wherein the longfiber reinforcement (a2) is at least one inorganic fiber selected fromthe group consisting of a glass fiber, rock wool, a metallic fiber and acarbon fiber, and/or at least one fiber selected from the groupconsisting of all aromatic polyamide fibers and all aromatic polyesterfibers.

(4) The long fiber-reinforced polymer alloy resin composition (C)according to the above items (1), (2) and (3), wherein the long fiberreinforcement (a2) is a glass fiber.

(5) The long fiber-reinforced polymer alloy resin composition (C)according to the above items (1), (2), (3) and (4) wherein the resindiluent (B) is composed of 60 to 75% by weight of the polyamide resin(b2) and 20 to 40% by weight of a crystalline polypropylene resin (b1)containing a modified propylene polymer (b11), the total amounts of saidcomponents (b1) and (b2) being 100% by weight.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a soft X-ray photograph of an injection molded flat sheetobtained from the long fiber-reinforced polymer alloy resin compositionof the present invention.

FIG. 1B is a soft X-ray photograph of an injection molded flat sheetobtained from a conventional fiber-reinforced resin composition.

BEST MODE FOR CARRYING OUT THE INVENTION

The long fiber-reinforced polymer alloy resin (C) according to theinvention is obtained by blending a specific master batch (A) and aspecific resin diluent (B), both of which are described in detailhereinafter.

Master batch (A)

The master batch (A) (sometimes referred to as "component (A)"hereinafter)used in the invention comprises a polyamide resin (a1) as aresin matrix (sometimes referred to as "resin matrix (a1)" or "polyamideresin matrix (a1)" hereinafter) and a long fiber reinforcement (a2).

The polyamide resin (al) used as a base of the resin matrix isconcretely exemplified as follows. As a matter of course, the polyamideresin (al) employable in the invention is not limited to the examplesbelow.

Ring-opening addition polymerization type resins:

polyamide-6, (PA 6), polyamide-11 (PA 11) and polyamide-12 (PA 12);

Co-condensation polymerization type resins: polyamide-6,6 (PA 66),polyamide-6,10 (PA610), polyamide-6,12 (PA 612) and MXD 6 (prepared fromm-xylenediamine and adipic acid);

Composites (Hybrids) of the above resins, such aspolyamide-6/polyamide-6,6co-condensate; and

mixtures of the above resins.

Of the above resins, preferred polyamide resins (nylons) are polyamide-6and polyamide-6,6 from the viewpoint of good balance between heatresistance and mechanical strength. For uses where compatibility withthe later-described resin diluent (B) and low water absorption property(waterresistance) are regarded as important, polyamide-11, polyamide-12,polyamide-6,10, polyamide-6,12 and MXD 6 are preferred. For uses whereheat resistance (heat distortion temperature) is regarded as important,MXD 6 is preferred.

As the long fiber reinforcement (a2) which is blended with the resinmatrix(a1) to allow the long fiber-reinforced resin composition of theinvention to have excellent tensile strength and repeated impactresistance, variousfibers described below can be properly employed. Thatis, any of inorganic fibers and organic fibers may be used as the longfibers of the long fiberreinforcement (a2). Examples of the inorganicfibers include glass fiber, rock wool, metallic fiber and carbon fiber.Examples of the organic fibersinclude all aromatic polyamide fibers(e.g., Aramid (trade name)) and all aromatic polyester fibers (e.g.,Kevler (trade name)).

These long fibers can be used in the form of a monofilament, but in manycases they are used in the form of a roving or end obtained by bundlinga large number of monofilaments using a binder.

The long glass fiber, that is most generally used as the reinforcementamong the above-mentioned long fibers, is described below. Also otherlongfibers can be used in a similar manner to that of in glass fiberexcept thespecial cases.

The glass long fiber reinforcement employable in the invention may be anordinary glass roving, that is supplied to reinforce resins. The rovingsuitably used in the invention has a mean fiber diameter of 6 to 30 μmand a bundle of 500 to 6,000 monofilaments, and preferably has a meanfiber diameter of 9 to 23 μm and a bundle of 1,000 to 4,000monofilaments. Two or more of the glass rovings doubled may be useddepending on the application. The length of the fibers in the longfiber-reinforced pellet (A) used in the invention is almost equal to thelength of the pellet, because the long fiber-reinforced pellet isobtainedby cutting a reinforced strand which is formed by pultrusion ofan endless fiber bundle.

For preparing the master batch (A) composed of the resin matrix (a1) andthe long fiber reinforcement (a2), that is, a long fiber-reinforcedresin composition which contains the resin matrix (a1) in a higherconcentrationthan the final concentration, the following processes (orapparatuses) known as "pultrusion processes (or apparatuses)" can beemployed without limitation.

A molten polyamide resin (a1) and a long fiber reinforcement (a2) of theroving type (long fiber bundle) are fed to a crosshead die in such amanner that the feed direction of the long fiber reinforcement crossesthedirection of the molten polyamide resin (a1). The long fiberreinforcement (a2) is then allowed to meander through plural barriers ormetallic bars which are arranged in parallel with each other and atregular intervals from each other along the flow path of the long fiberreinforcement (a2). The long fiber reinforcement (a2) is loosened whenit is brought into contact with the barriers or the metallic bars, andthe fibers thus loosened are impregnated with the molten resin, followedby taking up the resultant strands. After cooling, the strands arepelletized into pellets having a length of 3 to 30 mm, preferably 6 to25 mm, more preferably 9 to20 mm. The length of the pellet is equal tothe length of the long fiber reinforcement (a2), as described above.

It is preferred to avoid use of extremely short pellets, i.e.,reinforced pellets having a mean pellet length of less than 3 mm. Thereason is that the degree of improvement of the molded articles formedfrom the pellets having a mean length of less than 3 mm is small in anyof the physical properties including mechanical strength, impactresistance and repeated impact resistance properties. Also the use ofextremely long pellets having a mean pellet length of more than 30 mm ispreferably avoided, because when they are used, the bite of the screwinto the pellets having been fed through the hopper tends to becomelower in the ordinary injection molding machine and moreover, separationbetween the pellets andthe diluent resin often takes place in thehopper.

Resin diluent (B)

The resin diluent (B) used in the invention has been substantiallypolymer-alloyed, and is obtained from a specific crystalline polyolefinresin (b1) and polyamide (b2).

The crystalline polyolefin resin (b1) comprises a modified olefincrystalline polymer (b11). In the invention, the entire crystallinepolyolefin resin (b1) may be the modified olefin crystalline polymer(b11).

In more detail, the modified olefin crystalline polymer (b11) has beensubstantially modified with an unsaturated carboxylic acid or itsanhydride or derivative (sometimes generically referred to as"unsaturatedcarboxylic acids" hereinafter) serving as a modifier. Themodified olefin crystalline polymer having been substantially modifiedwith unsaturated carboxylic acids may be a single substance of amodified propylene crystalline polymer obtained by graft reaction of acrystalline polyolefinresin with a modifier, or may be a mixture of themodified propylene crystalline polymer and an unmodified crystallinepolypropylene resin.

Examples of polymers used as bases for the modified olefin crystallinepolymer (b11) include polyethylene, polypropylene, poly-1-butene andpoly-4-methyl-1-pentene. Of these, particularly preferred ispolypropylene. The olefin polymer used as a starting material of themodified crystalline olefin polymer (b11) or used as the unmodifiedolefincrystalline polymer is preferably a crystalline homopolymer or acrystalline copolymer of two or more olefins.

Examples of the unsaturated carboxylic acids serving as modifiersinclude at least one of acrylic acid, methacrylic acid, maleic acid,itaconic acid, tetrahydrophthalic acid, norbornenedicarboxylic acid, andat least one of anhydrides of these acids such as maleic anhydride,itaconic anhydride, tetrahydrophthalic anhydride andnorbornenedicarboxylic anhydride. Of these, maleic anhydride is mostpreferred from the viewpointof practical performance. Derivatives ofthese acids are also employable. The graft reaction of the olefincrystalline polymer with the modifier is preferably carried out in thepresence of a radical initiator.

In the resin diluent (B), any modified olefin crystalline polymer (b11)maybe used so long as it is substantially chemically reacted with thepolyamide resin (b2) so as to be polymer-alloyed. The modified olefincrystalline polymer (b1) may be another modified olefin crystallinepolymer having been modified with unsaturated carboxylic acids than theaforesaid graft modified olefin crystalline polymer, e.g., an ionomerresin, or it may be a polymer having, in addition to the carboxyl group,agroup which is another polar group than the carboxyl group and is ableto be linked to at least one of the amino group and the carboxyl group.

In the modified olefin crystalline polymer (b11) in the invention, theunits of the unsaturated carboxylic acids (modifiers) grafted to theolefin crystalline (co)polymer (b1) (i.e., base of the modified olefincrystalline polymer) are contained in an amount of usually 0.01 to 1% byweight, preferably 0.05 to 0.5% by weight.

As the polyamide resin (b2) used for forming the resin diluent (B),variouspolyamides exemplified above for the resin matrix (al) areemployable. It is preferred to use the same polyamide resin as thepolyamide resin (a1) of the resin matrix (a1).

In the present invention, the crystalline polyolefin resin (b1) and thepolyamide resin (b2) are melt kneaded to substantially form chemicallinkage between the modified propylene crystalline polymer (b11) and thepolyamide resin (b2), whereby a polymer-alloyed resin diluent isobtained.The expression "to substantially form chemical linkage" meansthat an experimental result in which the ratio of the boiling xyleneextraction residue in the product is higher by a significant differencethan the ratio of the polyamide resin (b2) added to the sum of (b1)+(b2)is observed.

This phenomenon indicates that the polypropylene molecules are notextracted and still remain owing to the occurrence of a chemical linkagebetween the polypropylene molecules and the polyamide molecules. Inother words, because of the chemical linkage between the modifiedpropylene crystalline polymer and the polyamide resin, the modifiedpropylene crystalline polymer comes to be hardly extracted.

The polymer-alloyed resin diluent (B) can be also prepared by anotherprocess comprising melt kneading the crystalline polyolefin resin (b1),the unsaturated carboxylic acid (preferably maleic anhydride) as themodifier and the polyamide resin (b2) together to substantially form achemical linkage between the modified polyolefin crystalline polymer(b11)and the polyamide resin (b2) to such a degree that theabove-described phenomenon is experimentally observed.

In the polymer-alloyed resin diluent (B), the crystalline polypropyleneresin (b1) is contained preferably in an mount of 20 to 45% by weight.Theamount of not more than 15% by weight should be avoided, because therepeated impact properties of the molded article obtained from the finalcomposition are reduced (see: Comparative Example 2). The lowering ofthe repeated impact properties is presumably caused by the amount of thecrystalline polypropylene resin (b1) being smaller than the lower limit.

On the other hand, the amount of the crystalline polypropylene resin(b1) contained in the polymer-alloyed resin diluent (B) exceeding 45% byweightshould be also avoided, because the mechanical strength and therepeated impact properties are lowered even if the amount of thecomponent (b1) contained in the final composition is within the rangedefined by the invention. That is, even if the amount of the component(b1) in the final composition is within the range defined by theinvention, the fact that the amount of the crystalline polypropyleneresin (b1) is more than 45% byweight means that the amount exceeds 50%by volume.

As a result, it is presumed that the crystalline polypropylene resin(b1) contributes to the matrix phase and the polyamide resin (a1)+(b2)!contributes to the disperse phase to form two phase (sea-island)structureconsisting of an island of the polyamide resin in thepolypropylene resin matrix. For this reason, the melting point of thepolymer-alloyed resin diluent (B) becomes equal to the melting point ofthe crystalline polypropylene resin (b1) which forms the resin diluent,and consequently folding of the long fibers can be undoubtedly inhibitedin the molding process as described in Japanese Patent Publication No.60780/1993.

However, the above-mentioned component ratio makes it difficult toprepare a uniform polymer alloy from the polyamide resin (al) serving asthe resinmatrix in the master batch, the polyamide resin (b2) forforming the resin diluent (B) and the modified propylene crystallinepolymer (b11), so that the molded article obtained from the finalcomposition (c) is barely improved in mechanical strength and repeatedimpact resistance properties.

Long fiber-reinforced polymer alloy resin composition (C)

The long fiber-reinforced polymer alloy resin composition (C) of theinvention is prepared by diluting the master batch (A) with thepolymer-alloyed resin diluent (B). Specifically, the composition (C) canbe prepared by dry blending pellets of both components. Further, it isalso possible that the strands of the master batch (A) formed by theaforesaid pultrusion are coated with the polymer-alloyed resin diluent(B)by means of extrusion coating and then pelletized.

The dilution should be carried out in such a manner that the amount ofthe fiber reinforcement (a2) contained in the final composition (C) isin the range of 10 to 60% by weight and the amount of the crystallinepolypropylene resin (b1) contained in other resin components(a1)+(b1)+(b2)! other than the fiber reinforcement (a2) in the finalcomposition is in the range of 20 to 45% by weight. If the amount of thecrystalline polypropylene resin (b1) is not more than 17% by weight(Comparative Example 7) or more than 45% by weight, the mechanicalstrength and the repeated impact resistance are lowered. Therefore, suchcase should be avoided. It is unfavorable that the amount of the fiberreinforcement (a2) is not more than 5% by weight, because a satisfactoryreinforcing effect cannot be given to the molded article (ComparativeExample 6). It is also unfavorable that the amount of the fiberreinforcement (a2) is not less than 70% by weight, because thereinforcingeffect given to the molded article gets saturated, resultingin economical disadvantages. Moreover, the amount of the crystallinepolypropylene resin(b1) is relatively reduced, resulting in lowering ofthe repeated impact resistance properties.

For molding the long fiber-reinforced polymer alloy resin composition ofthe invention into various articles, injection molding is optimum. Inthe injection molding, a screw having a L/D (ratio of screw length (L)to screw diameter (D)) of about 8 to 25 and a compression ratio of about1.5 to 2.5 is used.

When injection molding under the above conditions, the effects sought inthe present invention can be sufficiently attained, that is, the longfibers can be highly dispersed in the molded article, and the moldedarticle can be sufficiently improved in tensile strength and repeatedimpact strength (impact times in the durability test).

EXAMPLE

(1) Dispersibility of long fibers in molded article

The resin composition was injection molded into a flat sheet, and thestateof long fibers dispersed in the flat sheet was observed by means ofsoft X rays. The results are classified into the following groups.

AA (good): The long fibers are well dispersed and no bundle of longfibers is found.

BB (bad): The long fibers are locally present and a large number of longfiber bundles are found.

FIGS. 1A and 1B are copies of typical photographs showing the state ofthe long fibers practically dispersed in the molded article. FIG. 1A isa softX-ray photograph of a molded article produced from a compositionof the invention that is classified as good in dispersibility. FIG. 1Bis a soft X-ray photograph of a molded article produced from acomposition of each comparative example that is classified as bad or alittle bad in dispersibility.

(2) Tensile strength

The tensile strength was measured in accordance with JIS K-7113. In thistest, a specimen of JIS No. 1 was used.

(3) Repeated impact resistance properties

An Izod test specimen described in JIS K-7110 was set on an Izod impacttester. To the specimen, a hammer of 40 kg was repeatedly brought downat an angle of 75 degrees until the specimen was broken, and the numberof times of bringing the hammer down until the specimen was broken wascounted.

(4) Resin flow starting temperature

Measuring apparatus: Shimazu flow tester CFT-500 type

Measuring method: uniform rate heating method

Measuring conditions: heating rate=3° C./min, load=100 kgf, L/D ofdie=10/0.5

(5) Confirmation of chemical linkage formation

As for the resin diluent pellets (B), whether the chemical linkage wasformed or not was ascertained by a boiling xylene extraction method.That is, the sample pellets of 5 g were extracted with boiling xyleneand the extraction residue was measured. Judgment of the chemicallinkage formation was made based on the following two criteria. Themixing ratio of the polyamide resin described below means a valueexpressed by (b2)/{(b1)+(b2)}.

No chemical linkage exists: when the residue is almost the same as themixing ratio of the polyamide resin.

Chemical linkage exists: when the residue is larger than the mixingratio of the polyamide resin by not less than 10 % by weight.

Example 1-4, Comparative Examples 1 and 2

Into a crosshead die equipped on the tip of an extruder, a moltenpolyamideresin (al) as a resin matrix and a glass long fiber roving as along fiber reinforcement (a2) were introduced to produce strands bypultrusion in which the fiber bundle of the roving was loosened intofibers and the fibers were impregnated with the molten resin in the die.The strands werecut into pellets having a mean length shown in thefollowing tables, to obtain long fiber-reinforced pellets. The longfiber-reinforced pellets (A) thus obtained were master batch pellets (A)wherein 80% by weight of the glass long fibers were contained in PA 6.

In the above preparation of the master batch pellets (A), PA 6 (tradename:CM1007, available from Toray Industries, Inc.) was used as thepolyamide resin (a1), and a glass long fiber roving (a2) (mean singlefiber diameter: 17 μm, number of filaments in a strand: 4,000, tex yarnnumber count: 2,310 g/km, available from Nippon Electric Glass Co.,Ltd.) was used as the long fiber reinforcement (a2).

Separately, into an extruder were introduced a modified propylenecrystalline polymer (b11) obtained by graft reaction with maleicanhydride(b12) (amounts of maleic anhydride units: 0.3% by weight (=0.06meq)) and the aforementioned PA 6 (b2) in a given ratio shown in thefollowing tables, and they were melt kneaded in the extruder at 250° C.to substantially form a chemical linkage therebetween, so as to obtain apolymer-alloyed resin diluent (B). The resin diluent (B) was extrudedand cut into a given length. Thus, glass long fiber-reinforced pellets(mean length: 3 mm) were prepared.

Then, 50% by weight of the former and 50% by weight of the latter weredry blended, and the blend was injection molded at a temperature of 250°C. by means of an injection molding machine (L/D: 20, compression ratio:1.8), to prepare flat sheets and other various test pieces (specimens).The results are set forth in Table 1.

Examples 5 and 6, Comparative Examples 3-8

A final composition (C) was prepared in the same manner as in Example 1except that the amounts of the polyamide resin (a1) used as the resinmatrix and the glass long fiber reinforcement used as the fiberreinforcement (a2) in the resin master batch (A) reinforced with theglasslong fiber reinforcement (a2), the mean length of the master batchpellets,the ratio of the polyamide resin (b2) to the crystallinepolypropylene resin (b1)+(b11)! in the polymer alloy diluent (B), andthe mixing ratio between the resin master batch (A) and the polymeralloy diluent (B) were varied to those shown in the following tables.The final composition (C) was molded into specimens in the same manneras in Example 1, which were evaluated in the same manner as inExample 1. The results are set forth inTable 2, though only the resultsin Comparative Example 8 are set forth in Table 3.

Example 7

Into an extruder were introduced 10% by weight of the modified propylenecrystalline polymer (b11) obtained by graft reaction with maleicanhydride, 20% by weight of a unmodified polypropylene resin (b1) and70% by weight of the same PA 6 (b2) as used in Example 1, and they weremelt kneaded in the extruder, to obtain a polymer-alloyed resin diluent(B). A final composition (C) was prepared in the same manner as inExample 1 except that the polymer-alloyed resin diluent (B) was used inthe form of pellets. The final composition (C) was molded into specimensin the same manner as in Example 1, which were evaluated in the samemanner as in Example 1. The results are set forth in Table 3.

Example 8

Specimens were prepared in the same manner as in Example 1 except thatboththe resin master batch (A) reinforced with the long fibers and thepolymer-alloyed resin diluent pellets (B) were prepared by the use of PA66 (trade name: CM3007, available from Toray Industries, Inc.) as thepolyamide resin (a1). The specimens were evaluated in the same manner asin Example 1. The results are set forth in Table 3.

Comparative Example 9

Into an extruder having a first hopper as an ordinary hopper and asecond hopper which was provided on the barrel in order to feed afiller, a mixture of a modified propylene crystalline polymer (b11)obtained by graft reaction with maleic anhydride and the same PA 6 (a1)as used in Example 1 mixing ratio: 22/78 (the former/the latter, % byweight)! was introduced through the first hopper.

Through the second hopper, chopped glass strands (mean single fiberdiameter: 13 μm, mean length of chopped strands: 3 mm, available fromNippon Electric Glass Co., Ltd.) were introduced. The contents in theextruder were melt kneaded and extruded into strands. The strands werethen cut to obtain reinforced pellets having a mean length of 3.5 mm(containing 40% by weight of the glass fiber reinforcement).

The mean length of the fiber reinforcement remaining in the reinforcedpellets was measured, and it was 0.88 mm. Using the reinforced pellets,specimens were prepared in the same manner as in Example 1 except thatthepellets were not subjected to dilution with a diluent. The specimenswere evaluated in the same manner as in Example 1. The results are setforth inTable 3.

Comparative Example 10

Into the same extruder as used in Comparative Example 9, the same PA 6(a1)as used in Example 1 was introduced through the first hopper and thesame chopped glass strands (a2) as used in Comparative Example 9 wereintroduced through the second hopper. The contents in the extruder weremelt kneaded and extruded into strands. The composite strands thusobtained were cut to prepare master batch pellets (A) having a meanlengthof 3.5 mm. These master batch pellets (A) were polyamide resin(a1) pelletscontaining 60% by weight of the glass fiber reinforcement.

The mean length of the fiber reinforcement remaining in the master batchpellets (A) was measured, and it was 0.85 mm. Then, 65% by weight of themaster batch pellets (A) and 33% by weight of the same diluent pellets(B), as used in Example 1, were dry blended, and the amount of the glassfiber reinforcement in the final composition (C) and the amount of thecrystalline polypropylene resin (b1)+(b2)! in the final resin componentwere adjusted to the same values as in Comparative Example 9. The finalcomposition (C) thus obtained was injection molded in the same manner asin Example 1 to prepare flat sheets and other various test pieces(specimens), which were evaluated in the same manner as in Example 1.The results are set forth in Table 3.

View on the experimental results!

In Examples 1 to 8 according to the invention, the dispersibility of thefiber reinforcement (a2) in the resulting molded articles was good, andthe molded articles were excellent in repeated impact resistanceproperties as well as in tensile strength (see: Tables 1, 2 and 3).

In Comparative Example 1, the ratio of the modified propylenecrystalline polymer (b11) to the resin diluent (B) was too small, andalso the amount of the modified propylene crystalline polymer (b11)contained in the finalcomposition (C) was too small. The molded articleswere poor in repeated impact resistance properties, though tensilestrength thereof was improved(see: Table 1).

In Comparative Example 2, the ratio of the modified propylenecrystalline polymer (b11) to the resin diluent (B) was too large, andthe resulting molded articles were unsatisfactory in both tensilestrength and repeated impact properties (see: Table 1).

In Comparative Example 3, only the modified propylene crystallinepolymer (b1) (not polymer-alloyed) was used as the resin diluent (B),and the resin diluent (B) having a melting point lower than that of thefirst thermoplastic resin (A) was combined with the resin (A). Thoughthe final composition had a component ratio within the range defined bythe invention, the resulting molded articles were unsatisfactory in bothtensile strength and repeated impact resistance properties (see: Table2).

In Comparative Example 4, a master batch (A) of a long fiber-reinforcedresin was prepared by the use of the modified propylene crystallinepolymer (b11) as the resin matrix (a1), and to the master batch (A) wasadded a polyamide resin (b2) as the diluent (B). Though the finalcomposition (C) had a component ratio within the range defined by theinvention, the resulting molded articles were not improved at all inboth tensile strength and repeated impact resistance properties (see:Table 2).

In Comparative Example 5, the pellet length of the master batch (A) wastoolong. In the hopper of the molding machine, separation between themaster batch pellets (A) of the long fiber-reinforced resin and theresin diluent(B) took place, and hence there was found large variabilityamong the resulting molded articles, that is, molded articles of uniformquality were not obtained (see: Table 2).

In Comparative Example 6, the amount of the glass long fiberreinforcement (a2) contained in the final composition (C) was too small,and resulting molded articles were poor in each of tensile strength andrepeated impact strength (see: Table 2).

In Comparative Example 7, the amount of the glass fiber reinforcement(a2) contained in the final composition (C) was too large. Though theresultingmolded articles showed high tensile strength, they were low inrepeated impact strength because the amount of the modified propylenecrystalline polymer (b11) in the final composition (C) was too small(see: Table 2).

In Comparative Example 8, the long fiber-reinforced resin was preparedby using, as a matrix (=master batch (A)), a polymer alloy resinobtained by melt kneading PA 6 (a1) and the modified propylenecrystalline polymer (b11) prepared by the graft reaction with maleicanhydride. In this example, any resin diluent (B) was not used. Thoughthe component ratio ofthe final composition was within the range definedby the invention, the dispersibility of the fiber reinforcement (a2) inthe molded articles was poor, and the molded articles did not exhibittensile sought (see: Table 3).

In Comparative Example 9, the specimens were prepared by the use of thesame matrix as in Comparative Example 8 except for using short fibers asthe glass fiber reinforcement. The specimens were inferior to thespecimens prepared from the final composition (C) of the invention ineachof tensile strength and repeated impact resistance properties (see:Table 3).

In Comparative Example 10, the polymer-alloyed specific resin diluent(B) according to the invention was added to the master batch (A)obtained by the use of short fibers as the fiber reinforcement. However,the resultingspecimens were not improved at all in each of the tensilestrength and the repeated impact strength as compared with those ofComparative Example 9 (see: Table 3).

                  TABLE 1    ______________________________________    Experiment No.                     Comparative                       Example         Example    Content of Experiment                   1      2      3    4    1    2    ______________________________________    Amount of GF in final                   40     40     40   40   40   40    composition (wt %)    Amount of PP in final                   25     33     33   33   13   42    resin (wt %)    Ratio of master batch (A)                   50     50     50   50   50   50    (wt %)    (a1) Matrix resin (wt %)                   PA6    PA6    PA6  PA6  PA6  PA6                   20     20     20   20   20   20                   --     --               --   --    (a2) GF          (Amount (wt %)                       80     80   80   80   80   80          (Mean length (mm)                       10     10    6   25   10   10    Ratio of resin diluent (B)                   50     50     50   50   50   50    (wt %)    PP  (b1) + (b11)! ratio (wt %)                   30     40     40   40   15   50    PA (b2) ratio (wt %)                   70     60     60   60   85   50    Polymer-alloying (exist or                   exist  exist  exist                                      exist                                           exist                                                exist    not)    Flow starting temperature    (°C.)    ((a1)          236    236    236  236  236  236    ((B)           236    236    236  236  236  181    Fiber dispersibility in molded                   AA     AA     AA   AA   AA   AA    article (-)    Tensile strength of molded                   274    272    270  275  279  193    article (MPa)    Repeated impact resistance                   144    123    105  141  32   31    property of molded article    (number of times)    ______________________________________    GF: glass fiber reinforcement

                  TABLE 2    ______________________________________    Experiment No.            Comparative                    Example   Example    Content of Experiment                5      6      3    4    5    6    7    ______________________________________    Amount of GF in final                15     56     40   42   40    5   70    composition (wt %)    Amount of PP in final                29     27     33   31   33   35   17    resin (wt %)    Ratio of master batch                38     70     80   60   50   17   87    (A) (wt %)    (a1) Matrix resin                PA6    PA6    PA6  PA6  PA6  PA6  PA6    (wt %)      60     20     50   30   20   70   20    (a2) GF          (Amount   40     80   50   70   80   30   80          (wt %)          (Mean length                    10     10   10   10   35   10   10          (mm)    Ratio of resin diluent                62     30     20   40   50   83   13    (B) (wt %)    PP  (b1) + (b11)! ratio                40     40     100  --   40   40   40    (wt %)    PA (b2) ratio (wt %)                60     60     --   100  60   60   60    Polymer-alloying                exist  exist  not  not  exist                                             exist                                                  exist    (exist or not)            exist                                   exist    Flow starting    temperature (°C.)    ((a1)       236    236    236  181  236  236  236    (B)         236    236    181  236  236  236  236    Fiber dispersibility in                AA     AA     AA   AA   AA   AA   AA    molded article (-)    Tensile strength of                149    284    200  159  --   52   271    molded article (MPa)    Repeated impact    resistance property of                74     147    12   10   --    1   43    molded article    (number of times)    ______________________________________    GF: glass fiber reinforcement

                  TABLE 3    ______________________________________    Experiment No.             Comparative                     Example   Example    Content of Experiment                 7      8      8      9      10    ______________________________________    Amount of GF in final                 40     40     40     40     40    composition (wt %)    Amount of PP in final                 25     33     33     22     22    resin (wt %)    Ratio of master batch (A)                 50     50     100    100    67    (wt %)                            (short)                                             (short)    (a1) Matrix resin (wt %)                 PA6    PA66   PA6, MPP                                      PA6, MPP                                             PA6                 20     20     ALY 60 ALY 60 40    (a2) GF          (Amount    80     80   40     40     60          (wt %)          (Mean length                     10     10   10     0.88   0.85          (mm)    Ratio of resin diluent (B)                 50     50     --     --     33    (wt %)    PP  (b1) + (b11)! ratio                 30     40     --     --     40    (wt %)    PA (b2) ratio (wt %)                 70     60     --     --     60    Polymer-alloying (exist                 exist  exist  not    not    exist    or not)                    exist  exist    Flow starting temperature    (°C.)    ((a1)        236    277    236    236    236    ((B)         236    277    --     --     236    Fiber dispersibility in                 AA     AA     BB     AA     AA    molded article (-)    Tensile strength of                 273    271    167    153    155    molded article (MPa)    Repeated impact                 138    125    42     3      2    resistance property of    molded article    (number of times)    ______________________________________    GF: glass fiber reinforcement    ALY: polymer alloy    MPP: modified propylene polymer    Short: short fiber reinforcement

EFFECT OF THE INVENTION

The effects of the long fiber-reinforced resin composition (C) accordingtothe present invention are described below.

(1) The long fiber reinforcement exhibits high dispersibility in themoldedarticle, and hence the molded article is prominently good in bothtensile strength and repeated impact strength.

(2) Because of its excellent mechanical strength and repeated impactresistance properties, the long fiber-reinforced resin composition (C)of the invention can be favorably used for various industrial parts suchas vehicle parts (e.g., automobile parts such as bumpers, wheel caps andunder covers, impellers of outdoor fans or cooling towers, and electricpower tool parts.

(3) According to the injection molding method, the effects sought forthe invention, that is, uniform dispersibility of the long fibers in themolded article and improvements in tensile strength and repeated impactresistance properties (impact times in the durability test) of themolded article can be all realized to a high degree.

What is claimed is:
 1. A long fiber-reinforced polymer alloy resincomposition (C) obtained by blending:a master batch (A) comprising along fiber reinforcement (a2) having a length of 3 to 30 mm in a resinmatrix (a1) comprising a polyamide resin, and a substantiallypolymer-alloyed resin diluent (B) obtained by melt kneading 20 to 45% byweight of a crystalline polyolefin resin (b1), said crystallinepolyolefin resin (b1) comprising a modified olefin crystalline polymer(b11) having been substantially modified with unsaturated carboxylicacids, and 55 to 80% by weight of a polyamide resin (b2); in which theamount of the long fiber reinforcement (a2) is in the range of 10 to 60%by weight, and the amount of the crystalline polyolefin resin (b1) inother resin components ((a1)+(b1)+(b2)) than the long fiberreinforcement (a2) is in the range of 20 to 45% by weight.
 2. The longfiber-reinforced polymer alloy resin composition (C) as claimed in claim1, wherein the resin diluent (B) comprises 60 to 75% by weight of thepolyamide resin (b2) and 25 to 40% by weight of the crystallinepolyolefin resin (b1), the total amounts of said components (b1) and(b2) being 100% by weight.
 3. The long fiber-reinforced polymer alloyresin composition (C) as claimed in claim 1, wherein the long fiberreinforcement (a2) includes at least one inorganic fiber selected fromthe group consisting of a glass fiber, rock wool, a metallic fiber and acarbon fiber, and/or at least one fiber selected from the groupconsisting of all aromatic polyamide fibers and all aromatic polyesterfibers.
 4. The long fiber-reinforced polymer alloy resin composition (C)as claimed in claim 1, wherein the long fiber reinforcement (a2)includes a glass fiber.
 5. The long fiber-reinforced polymer alloy resincomposition (C) as claimed in claim 1, wherein the resin diluent (B)comprises 60 to 75% by weight of the polyamide resin (b2) and 25 to 40%by weight of a crystalline polypropylene resin (b1) containing amodified propylene crystalline polymer (b11), the total amounts of saidcomponents (b1) and (b2) being 100% by weight.
 6. The longfiber-reinforced polymer alloy resin composition (C) as claimed in claim1, wherein said master batch (A) and said substantially polymer-alloyedresin diluent (B) are in the form of a pellet.
 7. The longfiber-reinforced polymer alloy resin composition (C) as claimed in claim6, wherein said master batch (A) is formed by pelletizing a bundle ofcontinuous reinforcements impregnated with said resin matrix (a1) andthe resultant pellet has a length equal to that of the long fiberreinforcement (a2).
 8. The long fiber-reinforced polymer alloy resincomposition (C) as claimed in claim 1, wherein said master batch (A) isin the form of a pellet and is coated with said substantiallypolymer-alloyed resin diluent (B).
 9. The long fiber-reinforced polymeralloy resin composition (C) as claimed in claim 8, wherein said masterbatch (A) is formed by pelletizing a bundle of continuous reinforcementsimpregnated with said resin matrix (a1) and the resultant pellet has alength substantially equal to that of the long fiber reinforcement (a2).